The invention relates generally to automatic braking system testers and brake bleeding devices and, more particularly, to a tester and brake bleeder of automatic braking systems which utilize a computer system and which are incorporated in airliners, such as the McDonnell Douglas MD 80, DC 9 and DC 10.
Many modern airliners utilize an automatic braking system (ABS) to automatically apply full braking power with ground spoiler deployment during a rejected takeoff and to automatically apply a preselected level of braking power with ground spoiler deployment during landing. For landing, the pilot may select one of three ABS land modes providing either minimum, medium or maximum braking force. For takeoff, the pilot may select the ABS take off mode which provides maximum braking force during rejected takeoff. Incorporation of the ABS obviates the likelihood that brake application is delayed or not fully applied in these situations. In addition, the ABS ensures that full, steady braking pressure is applied and that it is applied at the earliest time for optimum anti skid braking efficiency.
A testing system currently in use on the ABS for the above identified airliners is integrated in the computer used in the ABS and is known as (or identified as) the Built In Testing Equipment (BITE). However, the BITE system has a number of disadvantages which render its use less than satisfactory and require technicians to utilize additional testing procedures and equipment when troubleshooting the ABS. Specifically, the BITE is not a comprehensive testing system, and, therefore, it can produce misleading results. In addition, the BITE system is not capable of fully testing some components and some component circuits of the ABS. In this regard, the BITE cannot test components and circuits used in certain ABS modes (minimum/land, maximum/land and take-off), cannot test anti-skid wheel velocity transducers and cannot isolate ABS computer control unit (LRU) component malfunctions from wiring harness and position switch malfunctions. Consequently, technicians troubleshooting the ABS often must perform aircraft taxi runs or test flights. The instructions for using the BITE system are very complex and difficult to comprehend rendering the BITE system subject to improper use or misinterpretation of the results. In addition, in order to bleed the brake manifolds, the technician must use a separate bleeder device.
An ABS tester is thus needed that is capable of fully testing the ABS in all its operational modes. An ABS tester is also needed that is simple and easy to use and that is capable of differentiating between wiring, switch and other component system malfunctions. An ABS tester is also needed that is capable of being used to bleed the brake manifolds.